Following the trend in a growing number of US states, New York lawmakers are considering legislation that would expand the state’s police DNA database. Currently, New York law mandates DNA collection from those convicted of all felonies and specified misdemeanors, which is the same as in Florida, Michigan, Ohio and Utah. The new bill would have allowed state authorities to collect DNA from anyone convicted of a felony or any misdemeanor, as in California (and only California).

The expansion bill appears to be going nowhere for now. But it stalled in the state legislature last week not because of controversy over the incursion into civil liberties that it portends; instead, legislators could not agree whether defense attorneys should be given the same access to the data as prosecutors.

In fact, New York governors Spitzer, Paterson and now Cuomo have all supported this bill, which would double the size of the state database, because they apparently believe that more samples means more justice. Governor Cuomo characterized the law as essential to New Yorkers’ safety because “DNA has allowed us, with certainty, to convict the guilty, bring justice for victims and exonerate the innocent.”

Twenty-four state legislatures (by my count) have been so persuaded by this thinking that they have mandated DNA collection not only from convicts but from felony arrestees. As one Georgia police sergeant in support of collecting more DNA in his state put it, "[t]here’s definitely a benefit to seeing the database expand. . . . The more people who are in the database, the more hits you’re going to have.” He is indubitably right, but for the wrong reason.

The unfortunate reality is that as database size increases, the probability that an innocent person will be “matched” and thereby deemed guilty increases. An investigation into the Arizona DNA database revealed that out of 65,493 profiles, 122 pairs matched at nine chromosome loci, 20 pairs matched at ten loci, and two pairs matched at twelve loci. Research on the larger Illinois state database revealed that out of 220,000 profiles, a staggering 903 pairs matched at nine or more chromosome loci.

Fortunately, the push to expand DNA forensic databases has not gone without criticism. When Ohio Senate Bill 77 authorized DNA collection from felony arrestees, the ACLU of Ohio voiced concern and the Ohio Bureau of Criminal Identification and Investigation tried to devise a means by which those acquitted could have their DNA removed from the database. The state’s largest newspaper, the Cleveland Plain Dealer, editorialized that “requir[ing] DNA samples from felony suspects runs contrary to an important constitutional guarantee: the presumption of innocence.”

In New Jersey, Assemblyman Gary Chiusano similarly faced pushback after introducing a bill to allow DNA collections from arrestees last week. An editorial in a leading New Jersey newspaper commented that “Chiusano’s bill raises troubling questions about privacy and unreasonable searches....What if science eventually determines that a person with a certain DNA profile was more likely to commit a bank robbery. The next time TD Bank got pinched, would it be okay to print out a list of those individuals and start marching them to the precinct for questioning?” It may be that science is already headed this direction.

But these voices are often drowned out by enthusiasm for DNA evidence. And a pending federal bill would add a financial prize to the push for DNA database expansion by providing 5% bonuses in federal money to states in which authorities collect DNA samples from people arrested for specified major felonies. A 10% bonus would be given to states that collect DNA from arrestees for specified lesser crimes. Federal incentives are a powerful, and in this case, misguided tool.

New York Assemblyman Joseph Lentol (D-Brooklyn) said that he would not vote for the New York bill in question until there was “equal access to DNA” by both prosecutors and defense attorneys. But what good is equal access to a defective tool? Lentol argues that the database will “protect those that have been wrongfully convicted of crimes.” But protecting the innocent means first presuming their innocence and then carefully scrutinizing the evidence at hand, not just religiously trusting that prosecutor's DNA forensic evidence is infallible.